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Biomedical subjects

Michael R O'Rourke

Publications and source records attributed to Michael R O'Rourke.

15 recordsLinked to original sources
PubMed2006

The treatment of pelvic discontinuity with acetabular cages.

We sought to determine if acetabular cages prevented rerevision and loosening in acetabular reconstructions in the setting of pelvic discontinuity. We followed 15 patients with 16 acetabular cage reconstructions for an average 5 years (range, 2-8 years). Acetabular classifications included two Type 2C, six Type IIIA, and eight Type IIIB. We assessed Merle d'Aubigné scores, rerevisions, radiographic loosening, and complications. We treated seven patients with structural allograft and six patients with cancellous allograft. Five hips (31%) were revised or resected because of aseptic loosening (4 hips) and sepsis (1 hip) at an average 46 months. Three additional hips were loose. Merle d'Aubigné scores for pain and walking increased from 3.7 points preoperatively to 6.8 points at the final followup. Complications included one infection, four nerve palsies, and one dislocation. Acetabular cages in the setting of pelvic discontinuity were associated with a high failure rate at intermediate-term followup.

Acetabulum↗
PubMed2006

Managing bone loss in acetabular revision.

The management of bone loss encountered during acetabular revision remains challenging. In order to obtain a successful surgical result, preoperative planning is required to estimate the severity and location of bone defects. Most acetabular revisions can be treated with the use of a cementless hemispherical component. However, a successful surgical reconstruction requires component stability. Depending on the degree of bone loss, the surgical reconstruction may require the use of cancellous or structural bone graft, acetabular augmentation, an acetabular cage, a custom implant, or an acetabular transplant.

Acetabulum↗
PubMed2005

The role of implant constraint in revision total knee arthroplasty: not too little, not too much.

The goal of revision total knee arthroplasty is to restore the anatomical alignment of the knee and to provide a stable joint. Joint stability is obtained by balancing the various knee ligaments remaining at the time of revision surgery and by using an implant with added stability if necessary. Understanding the limits of the various designs available (cruciate retaining, cruciate substituting, valgus-varus constraining, and linked) should help the surgeon construct a stable and durable construct.

Arthroplasty, Replacement, Knee↗
PubMed2005

Blood management: issues and options.

Blood management in the perioperative period of the total joint arthroplasty procedure has evolved over the last 3 decades. Strategies have changed and are changing based on a better understanding of blood loss and blood replacement options in this patient population. Patient-specific options based on preoperative hemoglobin levels and patient comorbidities as well as anticipated blood loss have been developed and studied. Patient-specific blood management programs have provided cost-efficient care with low morbidity.

Algorithms↗
PubMed2005

The John Insall Award: unicompartmental knee replacement: a minimum twenty-one-year followup, end-result study.

UNLABELLED: We report the results of a minimum 21-year followup of a consecutive series of 103 patients who had 136 Marmor cemented unicompartmental knee replacements done between 1975 and 1982. Patients were evaluated clinically and radiographically. At minimum 21-year followup 14 patients (19 knees) were alive, 87 patients (115 knees) had died, and only two patients (two knees) were lost to followup. The average age at surgery was 70.9 years. The average followup Hospital for Special Surgery knee score was 58. The average Knee Society final followup clinical and functional scores averaged 72 and 53 points, respectively. Nineteen knees (14%) were revised during the 21-year followup period: nine for progression of disease, eight for loosening, and two for pain, at an average of 10.6 years (range, 1-22 years). Of the 19 knees in the 14 patients who were still alive at final followup, seven (37%) were revised: two for tibial loosening, four for disease progression, and one for pain. Unicompartmental knee replacements in this relatively older age group of patients performed well at minimum 21-year followup. Although we are encouraged by these results, only 22% were done in patients who were younger than 65 years at the time of surgery and the results in this group were significantly less durable. LEVEL OF EVIDENCE: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed2005

Cemented rotating-platform total knee replacement. a concise follow-up, at a minimum of fifteen years, of a previous report.

We previously evaluated 119 consecutive total knee arthroplasties that were performed in eighty-six patients with use of the cemented LCS (low contact stress) rotating-platform system with an all-polyethylene patellar component. The average age of the patients at the time of surgery was seventy years (range, thirty-seven to eighty-eight years). The purpose of this study was to report the updated results at a minimum follow-up of fifteen years. Thirty-seven patients (fifty-three knees) were living, and no patient was lost to follow-up. No knee was revised because of loosening, osteolysis, or wear. Three knees required a reoperation (two for periprosthetic fractures and one for infection). No component was revised as a part of the reoperations. Osteolysis was present in three knees. No knee had radiographic signs of component loosening, and there were no dislocated bearings. The average range of motion was from 1 degrees of extension to 105 degrees of flexion. The average clinical and functional Knee Society scores were 43 and 49, respectively, at the preoperative evaluation and 85 and 58 at the time of the final follow-up. We concluded that the cemented LCS rotating-platform knee performed well, with durable clinical and radiographic results at a minimum follow-up of fifteen years.

Activities of Daily Living↗
PubMed2004

Applying the ASRA guidelines to the use of low-molecular-weight heparin thromboprophylaxis in major orthopedic surgery.

Although low-molecular-weight heparin (LMWH) is a widely used form of thromboprophylaxis in orthopedic surgery, concerns remain over the concomitant use of regional anesthesia (RA)/postoperative regional analgesia (PRA) stemming from reports in the 1990s of spinal hematoma associated with this combination. One of the objectives of the Second American Society of Regional Anesthesia (ASRA) Consensus Conference was to address the safety of LMWH in combination with neuraxial anesthesia. The guidelines are designed in part to help orthopedic surgeons already using or contemplating the use of LMWH prophylaxis to avoid or minimize potential complications arising from its use with RA/PRA. Clinicians should consult the ASRA guidelines for recommendations on total daily dose, timing of the first postoperative dose, and dose schedule for anticoagulants used in conjunction with RA/PRA.

Analgesia↗
PubMed2004

Use of structural allografts in acetabular revision surgery.

Bone loss is a challenging problem with complex acetabular revisions. With an adequate biologic and mechanical environment, uncemented hemispheric component reconstructions have provided long-term durable results for acetabular revisions. Decisions about reconstructive options can be made with the aid of a classification system that addresses the location and severity of bone loss as it relates to achieving the prerequisites for biologic fixation with a hemispheric component. Structural allograft may be used to provide a mechanical environment that supports host bone ingrowth into an acetabular component. Alternatively, structural allograft may allow restoration of joint mechanics in situations where host bone loss precluded biologic fixation. We describe the indications and technique for the use of structural allograft in revision acetabular surgery.

Acetabulum↗
PubMed2004

Use of a constrained tripolar acetabular liner to treat intraoperative instability and postoperative dislocation after total hip arthroplasty: a review of our experience.

Constrained acetabular components have been used to treat certain cases of intraoperative instability and postoperative dislocation after total hip arthroplasty. We report our experience with a tripolar constrained component used in these situations since 1988. The outcomes of the cases where this component was used were analyzed for component failure, component loosening, and osteolysis. At average 10-year followup, for cases treated for intraoperative instability (2 cases) or postoperative dislocation (4 cases), the component failure rate was 6% (6 of 101 hips in 5 patients). For cases where the constrained liner was cemented into a fixed cementless acetabular shell, the failure rate was 7% (2 of 31 hips in 2 patients) at 3.9-year average followup. Use of a constrained liner was not associated with an increased osteolysis or aseptic loosening rate. This tripolar constrained acetabular liner provided total hip arthroplasty construct stability in most cases in which it was used for intraoperative instability or postoperative dislocation.

Adult↗
PubMed2002

Tibial post impingement in posterior-stabilized total knee arthroplasty.

Reports of posterior-stabilized total knee replacements have shown excellent clinical success. However, tibial post-femoral cam impingement has been seen in modular component retrievals. This finding has been associated with transmission of rotational forces to the modular tray-polyethylene interface with subsequent backside polyethylene wear and the development of osteolysis. Femoral cam-tibial post designs that allow hyperextension and limit rotational constraint may minimize this impingement. Technical considerations including the avoidance of femoral component flexion and posterior tibial slope will minimize anterior tibial post impingement.

Arthroplasty, Replacement, Knee↗
PubMed2002

Osteolysis associated with a cemented modular posterior-cruciate-substituting total knee design : five to eight-year follow-up.

BACKGROUND: Most intermediate and long-term studies of cemented posterior-cruciate-substituting total knee prostheses were performed with nonmodular tibial components. The purpose of this study was to evaluate the intermediate-term results of posterior-cruciate-substituting total knee arthroplasties in which a cemented modular tibial component had been used, with a particular focus on evaluating the prevalence of radiographic osteolysis. METHODS: Between 1992 and 1995, 176 consecutive primary total knee arthroplasties with use of the Insall-Burstein II system were performed in 134 patients at our institution. A modular metal-backed tibial component was inserted in 145 knees, and an all-polyethylene tibial component of the same design was inserted in thirty-one. Standard-terminology questionnaires were completed or Knee Society and The Hospital for Special Surgery scores were determined preoperatively and at the time of final follow-up, at an average of 6.4 years (range, 5.0 to 7.9 years). Initial postoperative radiographs were compared with those made at the time of final follow-up to assess component position, wear, radiolucent lines, and osteolysis. RESULTS: Ninety-two patients (128 knees) treated with the modular tibial component were alive at the time of final follow-up. No patient was lost to follow-up. Radiographs were available for 105 knees (82%). Three knees had been revised because of instability or infection; none had been revised because of loosening or osteolysis. The mean Knee Society clinical and functional scores were 85 points (range, 41 to 100 points) and 79 points (range, 30 to 100 points), respectively, at the time of final follow-up. According to The Hospital for Special Surgery score, 94% of the knees had a good or excellent result. Knee flexion averaged 113 degrees (range, 90 degrees to 130 degrees ) at the time of final follow-up. Osteolysis was present in seventeen (16%) of the knees with radiographic follow-up. Osteolysis did not develop in any knee in which an all-polyethylene tibial component had been used. Two knees (in one patient) were revised because of osteolytic lesions found at the time of follow-up for the study. Both of these knees had anterior wear of the tibial post due to impingement and backside tibial polyethylene wear. CONCLUSIONS: Modular Insall-Burstein II total knee prostheses were found to function well after five to eight years of follow-up. However, the high prevalence of osteolysis in patients who had good or excellent clinical scores is worrisome. Particular attention should be paid to preventing flexion of the femoral component, posterior slope of the tibial component, or hyperextension of the knee when posterior-cruciate-substituting total knee arthroplasty is performed. We also recommend routine follow-up radiographs after all total joint arthroplasties to detect asymptomatic osteolytic changes.

Aged↗